Marble lifting automation

[ddmckee54]

Yup, you are well on your way to having a fully automated marble pump.

Don

 

[Brian Rupnow]

Tonight was rotary table night. I put a divider plate on so I could turn EXACTLY 60 degrees between each hole. First I drilled the 1 1/4" cold rolled that will become the hub for the gear. The 6 holes in it will be tapped. Then without moving my set-up I was able to mount the outer rim and drill 6 holes with a 3/16" diameter drill and then counterbore with a 3/8" endmill. The plan is to thread the end of my six 3/16" diameter "spokes" on one end and put them thru the 3/16" holes in the outer rim, screw them into the hub, then cut them off flush with the rim outer diameter, assemble everything in a jig, and then mig weld the end of the spokes. That is what the 3/8" counterbore is for, to fill up with mig weld. Will it work?--I have no idea. After everything is welded in a jig, I will mount the 1 1/4" hub (which is left extra long at about 3") back into the lathe and turn the outer diameter of the rim to a proper fit to go into the inside the bronze that will have the gear teeth cut into it. I have drilled the holes 5/16" in from the face of the hub and the outer rim so I will be able to "clean up" the faces in my lathe.

 

[pkastagehand]

A little off track of what you're doing Brian but have you seen the Great Ball Contraptions that show up at Lego conventions? Search for GBC or Great Ball Contraption on youtube and other places. Lots of ideas if you ever want to try another. Some of them pretty crazy.

Paul

 

[Brian Rupnow]

Paul--I've only seen the wooden ones on Youtube. I don't think I want to make a career out of this one. Probably only a couple of lifting devices and return chutes. I know there are some monsters out there.---Brian

 

[ddmckee54]

Silly question about the jig for welding up the spokes of the wheel. Won't the 6 spokes self center the rim, or is the jig to keep the rim centered despite the welding stresses?

Don

 

[Brian Rupnow]

In theory the 6 spokes should keep everything centered. I have been burned by theoretical "should be's" enough times in the past that I will build a jig.

 

[Brian Rupnow]

This is very interesting!!! I may go into business making ships wheels. And as far as the comment that was made by someone who said "That hub will be self centering."--Nah, not even close. I am going to have to set the hub up in the lathe chuck and using my dial indicator, chase the outer rim around by tapping it until its close to being concentric, before I make up a jig for welding.

 

[Brian Rupnow]

Whenever somebody hears "Build a Jig" they automatically think of something complex. It isn't always that way. My jig for welding the gear was made from a piece of 1/2" aluminum plate. A 1/2" hole was drilled on center, a 1 3/8" counterbore .150" deep. and the outer edge turned away to leave a "spigot" that was the exact size of the inner ring diameter x 0.150 deep. I took a piece of 1/2" cold rolled steel about 2" long, drilled and tapped a 1/4"-20 hole in the end of it, then inserted it in the 1/2" bore in the end of my "hub" and cross pinned it there with a 1/8" spring pin. I set it up so that about 5/16" of the 1/2" rod extended past the face of my hub. That allowed me to set the entire built up pulley in the jig, run a 1/4" bolt thru a washer and thru the jig plate from the back side, and tighten the hub in place against the face of the 1 3/8" counterbore. The 1 3/8" counterbore was clearance on the hub o.d. because the actual locating was done by the 1/2" cold rolled. Then an assortment of welding clamps and c-clamps were used to clamp the outer rim tight against the jig.

 

[Brian Rupnow]

And this is how the welding went---In the second picture down, you can see the 1/8" spring pin which was holding the 1/2" diameter cold rolled in the hole in my hub.

 

[Brian Rupnow]

The welds were ground flush with my big stationary belt sander, then the welded up construction was put back in my lathe, the o.d turned to the correct diameter, and the bronze rim pressed and loctited in place. Then a few more cuts on the outer diameter of the bronze brought it down to the correct o.d. for a 108 tooth gear, and a couple of facing cuts to blend the exposed face.

 

[Brian Rupnow]

Of course, I still have the other side to contend with, and to do that I will put a longer piece of 1/2" cold rolled into the center of the hub, put the spring pin back in place, and then hold onto the 1/2" cold rolled to face the other side.

 

[Brian Rupnow]

The game plan has changed a little bit. I noticed when I was facing the 4130 outer rim and holding the hub in my 3 jaw chuck that I was getting some bad chatter. I think that may be related to the fact that the six 3/16" spokes have a certain amount of "springiness" to them. Now that I have a good face and shoulder on the built up part, I can put the reverse jaws in my chuck and hold onto the outside diameter to "face" the other side. Its late here now, and I won't do any actual machining until tomorrow, but this should give me a sturdier, less "springy" set up. I am leaving the hub as long as it is so I have something to hold onto with the chuck on my rotary table when I go to cut the gear teeth.

 

[Cogsy]

Brian - How well did the O.D. turn with the weld points? I know you ground them flush first, but I assume you had to machine them at least a little to true up the OD. I've never tried to machine welds as I thought they'd be too hard for HSS tools.

On another note, I had to take one of my daughters on a school excursion yesterday, to a science-y place, where they had several 'marble lifting devices' although scaled up to use bowling balls and croquet balls. Very cool to watch and was a highly popular activity with all the visitors. I can see many more additions to your machine in the future.

 

[Brian Rupnow]

Cogsy--I use 0.023" diameter fluxless wire in my mig welder. It seems to machine about the same as mild steel. Marble lifting machines are not really my "thing", but they do have a lot of unique and very intriguing mechanical components to them. I can see where one could get started on a simple one and end up making a career of it.---Brian

 

[Brian Rupnow]

My clear lexan tube arrived this week, so now I have to machine a saddle for it to attach it to the top of the machine where the marbles are expelled. They will accumulate in the clear lexan tube before spilling out the top to cruise down a ramp.

 

[Brian Rupnow]

I never had a single doubt
The marbles would go up the spout
I'm only half way done my friend--
I've yet to get them down again!!!

 

[vascon2196]

Looking awesome!

 

[Brian Rupnow]

The fickle finger of fate was waiting for me this morning!! I didn't feel like any major machining, so I had a big shop clean-up and then decided to set-up for cutting my 108 tooth gear. My mill table lacks about 3/8" of travel to fit the set-up in. My next resort will be to move everything to the outermost T-slot in the mill table. This creates a bit of a problem, because the hole spacing on my rotary table is such that the bolt nearest to me will have to hang out in the air. I guess that's why I have hold down (toe) clamps. Now I will go try and move everything over and see what happens.

 

[Brian Rupnow]

I'm not sure if I'm being rewarded for living a good clean life, or being punished for things I have done in the past. I was able to move everything out to the outer T-slot, and it fits. I only have 1/16" clearance between the top of the bronze gear and the underside of my mills head, but a miss is as good as a mile!!! I had to modify the end of a toe clamp to get it in under the chuck and still clear everything, but its in there, and its tightened down. I still have one bolt thru the rotary table housing engaged with the center T-slot. I thin k I'm just about ready to start cutting teeth----All 108 of them!!!

 

[Scott_M]

Brian
Aren't worried about the same "springiness" from the spokes causing a problem here ?
Is the gear tooth minor diameter bigger than that 3 jaw ? Can you move directly to the chuck ?

Scott